This function is for converting binary data into a hexadecimal string representation. This function is not for converting strings representing binary digits into hexadecimal. If you want that functionality, you can simply do this:
<?php
$binary = "11111001";
$hex = dechex(bindec($binary));
echo $hex;
?>
This would output "f9". Just remember that there is a very big difference between binary data and a string representation of binary.

viking coder

The simplest way to do a true hex2bin (not ascii 1s & 0s).
pack("H*", $hex);

stroppytux

The other way to do this pedram, is to do this:
$encoded= strrev(chunk_split(strrev(bin2hex("test@mail.com")), 2, '%'));

php_guru ät bestof däsh inter döt net

The function hexentities($str) of the previous post is equivalent to
<?= substr( chunk_split( bin2hex( " $str" ), 2, ";&#x" ), 3,-3) ?>
Also, I think that the <address> tag should be used for the whole paragraph (usually at document foot) and not as shortcut for <span class=email> or so (although it is an %inline; element), see e.g. http://www.w3.org/TR/html4/struct/global.html#h-7.5.6

rt

The easiest way of all to convert a hex string to ascii is:
<?
pack("H*", $your_hex_string);
?>

admin

Some gave a function to convert a hex code back into a simple text (human readable ASCII :P)
Some else gave a function that makes use of bin2hex to convert URLs into something like %12%34%56
Here is a function to go from the form %12%34%56 back into ASCII
Note that this function can easily be changed in order to transform any hex code into ASCII
<?
function _hex2text($str) {
$str = explode('%', $str);
array_shift($str);
$nmlstr = '';
foreach($str as $hexstr) {
$nmlstr .= chr(base_convert($hexstr, 16, 10));
}
return $nmlstr;
}
?>
'hope this helps :)
Regards
-Tsuna

In response to Patrik:
A simpler way to print a number in binary is to use base_convert().
<? echo base_convert($bin, 10, 2); ?>
If you need it to print all 32 bits (as your function does) you can just pad it out:
<? echo str_pad(base_convert($bin, 10, 2), 32, '0', STR_PAD_LEFT); ?>
The conversion is from base 10 because when $bin is passed to base_convert(), it is converted to a string, and the default representation is in decimal.
Hope this helps.

I wrote the function that is useful for sending emails for example in cyrillic encoding (wondows-1251, koi8-r and so on).
It converts every symbol in the string into hexadecimal presentation with "=" symbol as delimiter.
For example, the string "Ðåãèñòðàöèîííûé êîä äëÿ" will look like that:
=d0=e5=e3=e8=f1=f2=f0=e0=f6=e8=ee=ed=ed=fb=e9=20=ea=ee=e4=20=e4=eb=ff
I use it for encoding email subject, but it could be modified for anything else.
<?php
function hex4email ($string,$charset)
{
$string=bin2hex ($string);
$encoded = chunk_split($string, 2, '=');
$encoded=preg_replace ("/=$/","",$encoded);
$string="=?$charset?Q?".$encoded."?=";

return $string;
}
?>

tightcode

I was just browsing the above and with a little modification,
came up with the following which I believe to be more flexible:
<?php
function bin2hex($data) {
$corrected = ereg_replace("[^0-9a-fA-F]","",$data);
return pack("H".strlen($corrected),$corrected);
}
?>
This will make sure that whatever you pass, even if it is padded
at the extremeties or between pairs, should return the desired data.

I have found the above quoted-printable encoding function to be
extremely useful, and thank maxg for making a great function that is not already included in PHP.
(Pity it's hidden all the way over here when it could be found more easily in quoted_printable_decode() )
However, there is one missing character in the code that needs to be included:
Right after the ?Q? there needs to be an extra equal sign in order for the very first character to be translated by the e-mail software.
$string = "=?$charset?Q?=" . $encoded . "?=";
is correct.
I don't yet have enough experience to speak for other caveats or improvements, but your mileage may vary depending on the e-mail server.
- Luke

Here's a modified version of an earlier post (asc2bin and bin2asc) to convert an incoming ascii string to hex and out again. For example, this is really useful if you want to insert data into a mySQL database which contains both escaped and non-escaped characters. For example, if you want to store code snibbets in a mySQL text field:
printf("here's some \"text\".");
If you INSERT this into mySQL, it probably won't come out in friendly executable format, and you can't escape all double-quotes, nor can you strip out all the slashes. One solution is to just convert the string to hex, store it in hex, then convert back to ascii before using it in some way:
function asc2hex ($temp) {
$len = strlen($temp);
for ($i=0; $i<$len; $i++) $data.=sprintf("%02x",ord(substr($temp,$i,1)));
return $data;
}
function hex2asc($temp) {
$len = strlen($temp);
for ($i=0;$i<$len;$i+=2) $data.=chr(hexdec(substr($temp,$i,2)));
return $data;
}

francisco ffaria

function to search a character in a normal string change this for a hexadecimal and take the especifical char code in hexa and replace this char and return the string
<?php
function hex_replace($pCaracter,$sCaracter,$conteudo) {

A good option for creating strings with binary data for saving (for example saving an sql statement to a file) into text files or php code is to do the following:
<?php
$field=bin2hex($field);
$field=chunk_split($field,2,"\\x");
$field= "\\x" . substr($field,0,-2);
?>
this will convert your field (binary or not) into hex and then convert the hex into a string which may be placed in a php file:
FFFFFFFF -> \xFF\xFF\xFF\xFF